1. Field of the Invention
The present invention is related to valuating hydrocarbon reservoirs and more particularly to automatically supplying missing parameters for a newly identified reservoir and an uncertainty associated with each supplied parameter, parameters that are necessary for accurately selecting analogous reservoirs and valuating each new hydrocarbon reservoir.
2. Background Description
The total amount of material that is ultimately recoverable from each new hydrocarbon reservoir (production potential) and the cost of recovering that material, or capture difficulty, determine the inherent value of the reservoir. Until the material is actually recovered, however, that inherent value can only be estimated from different reservoir properties. Many of these reservoir properties may be known, and many of them may be unknown. Previously, estimates were based on existing reservoirs that have similar properties limited to those known for the new reservoir. These existing reservoirs with similar properties are known as “analogous reservoirs.” Typically, one or more experts identified and selected analogous reservoirs, based solely on experience and the known properties for the new reservoir. When enough is known about a new reservoir, however, what is known as a similarity function may be used to automate, or at least partially automate, selection.
Similarity functions have found many uses in the art for comparing members of a collection of objects, or population, and selecting those objects that, although they not identical, are recognizably similar. Instead of a true/false (1/0) result, a typical state of the art similarity function quantifies the similarity between two objects. So, in a typical state of the art approach to valuating reservoirs, an expert (or experts) first selected the analogous reservoirs. Then, the expert(s) selected similarity function parameters and weights based on personal knowledge and experience, perhaps using local search methods, such as gradient descent and genetic algorithms. The similarity function could then be applied to the analogous reservoirs to estimate the value of the new reservoir.
However, missing or unknown properties make selecting the closest analogous reservoirs guesswork at best, and further, make estimating the value error prone. A mis-valuation could lead to wasted resources, e.g., from passing on an undervalued reservoir to exploiting an overvalued reservoir. Missing parameters increase the likelihood of a mis-valuation.
Thus, there is a need for improved, more complete descriptions of new reservoirs used in valuating the new reservoirs; and, more particularly for supplementing incomplete descriptions of new reservoirs with fact based estimates of missing description parameters and providing an uncertainty associated with the estimates, such that the supplemented descriptions facilitate selecting existing hydrocarbon reservoirs as analogous, and valuating the new reservoirs with a known uncertainty as to the result.